Airborne nanoparticles filtration performance of fibrous media: A review

Although the fundamental concepts of fibrous filters are clearly understood for the capture of micron and submicron sized particles, basic questions arise when the particles to be captured are nanometer-sized. The purpose of this article is to compile an inventory of knowledge on the performance of fibrous media for capturing nanoparticles. In the first part of this review, the classical theory of fibrous filters is described for media in general, with a focus on the principles that apply to nanoparticles filtration. The recent breakthroughs reviewed include theoretical and empirical models for single fiber efficiency. In the second part, we present the classical models of pressure drop for both clean and clogged flat fibrous media as applied to nanoparticles filtration. We also include an extensive discussion about pressure drop across a particle deposit (cake) during surface filtration. In the third part, the impact of several parameters such as air flow rate, humidity, particle shape and morphology, fibers diameter, heterogeneous fibers, electrostatic forces, upstream particle concentration and temperature are reviewed in detail.